Touch screens, touch pads, series of touch buttons, and other capacitive touch sense devices determine the presence of a finger or other object relative to the device according to capacitive changes caused by the finger or object. Some capacitive touch sense devices are integrated with mechanical buttons in addition to the capacitive touch sense input. The FIG. 1A shows an example of a radial slider having integrated mechanical buttons.
Referring to FIG. 1A, the front surface 10 includes structures 15 associated with a capacitor array. As a finger slides over these structures 15 capacitive changes can be detected to track the movement and position of the finger relative to the structures 15. The back surface 11 includes dome switches 16. If the finger presses against the front surface 10 using a force exceeding a threshold, one of the dome switches 16 contacts a gimble plate thereby generating a corresponding signal.
Referring now to FIG. 1B, when a finger lightly touches position 21, and then thereafter slides along the path 22, a data output is registered. The data output matches the user's intended input by correctly identifying the path 23 extending from the originating position 24. The data output also correctly reports that no button presses took place.
Referring now to FIG. 1C, when a finger strongly presses against the position 31, a data output is registered. The data output indicates a press 33 on the upper dome, which matches the user's intended input (the button press at position 31). However, the data output also registers a touch 32, and possibly some small movement (not shown), via capacitive sensing. The user may have intended to only manipulate the upper dome switch; however, the presence of the finger near the corresponding capacitors causes the touch 32 to be registered whenever the press 33 is registered.
The data output identifying both the touch position 32 and the button press 33 is reported to a software application, and because the user did not intend the touch input, the software program receives partially invalid data. The disclosure that follows solves this and other problems.